Gummed paper and method of preparing



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May M, w35., G. R. ALDEN GUMMED PAPER AND METHOD OF PREPARING Filed April 29, 1931 fr X/ Patented May 14, 19.35V

PATENT f OFFICE `GUMMED PAPER AND Marilou or raEPAarNG Gardner E. Alden, Framingham, Mass., assigner to Dennison Manufacturing Company, Framingham, Mass., a corporation of Massachusetts Application April ze, 1931, serial No. 533,652

Claims.

This invention relates to gummed paper, and to a method of preparing the same, especially to prevent curling.

In the usual manufacture of gummed papers,- 5 it is customary to' coat a sheet of paper with fluid compositions such as dextrine,` animal glue, fish glue, or the like. This penetrates the fibrous surface of the paper sheet and also forms a superficial continuous layer of adhesive. Upon drying, this surface'coating becomes relatively hard and brittle, and shrinks appreciably. Such shrinkage of the outer adhesive layer may be greatly in excess of any shrinkage of the paper, even though the latter is initially vey wet. The

' intermediate layer of impregnated fibres firmly holds the adhesive and .paper layers, together,l `rzut may shrink somewhat less on a count of the intervening mass of libres embedde in the adhesive matrix. The paper sheet, beiig usually 0 somewhat moistened by the fluid composition, shrinks slightly upon drying, but not enough to compensate for the shrinkage of theadhesive and hence yields to the shrinkage stresses of the drying adhesive layer and the sheet as a whole tends to curl toward the glue side.

The diiiicultiesfthus introduced in the preparation and subsequent ,use of gum coated papers are obvious, and numerous expedients have been adapted to overcome them. Of these, one of the most commonly employed is that of breaking the paper by drawing it,un der considerable tension over a sharp edge. This tends to crack the impregnated surface of the paper sheet as well asthe outermost layer of" hardened guinl or glue. But owing to the intermediate, glue im` pregnated layer of fibre at the surface of the paper sheet, it requires a considerable tension upon the sheet to thus bend the paper sharply I enough `adequately to break up the structure of the adhesive layer and of 'the glue impregnated layer of fibre. Such excessive tension frequently causes complete rupture or tearing ofthe sheet, with attendant waste of material, time ,and labor in again threading and starting the sheet through the breaking apparatus. l s,

It is therefore an object of this invention to prepare a sheetof gummed paper in which the gum coating may be more vuniformly andmorev effectively broken, so' as to overcome the tendency of the same to curl.j It is also an object to provide a'discontinuous superciallayer of the adhesive. It is a further object to insure the adhesion of the gum coating to the paper sheet, l both prior to and after its application and use.

, invention, the sheet may be provided with a sub- Other objects will appear from the vnf: disclosure.

In accordance with the present invention, a sheet of paper or like flexible material is treated with a resistant material such as wax,\ (as by printing or spraying the same in a suitable condition, either as a fused liquid or as a solutionI or emulsion), in the form of a finely divided, open pattern or stippling of discrete particles, or a reticulated pattern of iibriform lines; and applying over the same a substantially continuous -layer of the fluid gum or adhesive composition.

The thus treated sheet may then be allowed to dry and harden. It is then preferably subjected.V to the usual breaking operation in any usual andk convenient manner. In so doing, it is found that a relatively light tension or strain across the breaking bar is sufficient to shatter'the outer continuous layer of adhesive with innumerable fine lines or fissures, without loosening it from the sheet, without causing wrinkles or creases therein, and at the same time minimizing the liability of tearing. 1

It will be understood that the advantages of the invention may also be realized in part by-ap- 25 plying to the otherwise untreated sheet an open' pattern, (reticulated or stippled) of the adhesive, with or without subjecting to a subsequent breaking operation. In a further modification of the 30 stantially continuous layer of the resist or `wax like material and then (by suitably modifying the adhesive as hereinafter described) applying a continuous or discontinuous layer of the adhesivel thereto, followed by the breaking operation'. In such modification however the wax like material `ceases to'act as a resist and adheres to the superposed adhesive layer. But the procedure described above is preferred whererthe paper is'intrinsically absorbent of moisture and where a continuous adhesive film or surface is desired.

'A typical instanc/e of carrying out the invention will be described with reference to the ac- -companying drawing, in which:

Fig. `lis aside elevation of suitable apparatus for preparing and breaking the gummed sheet;

Fig.. 2 is a plan view of the sheet as prepared with the resist, showing a reticulated pattern; Y Fig. 3 is a plan view of a sheet, as'prepared with resist, showing' a dispersed or stippled pat- 50 tern;

Fig. 4 is anenlarged cross-section of the flnished sheet, before breaking; and

Fig. 5 is e. cross-section1 of the anishd ksheet after breaking.

Referring to the drawing, a sheet of paper I may be drawn from roll 2 and passed over guide roll 3 which directs and holds it firmly against a printing drum 4. While on the drum 4 the sheet may be printed witha resist from tank 5, by means of an intaglio printing roll 6, which dips therein. The composition of a suitable resist may be prepared as follows: 45 lbs. of an emulsion of 40%vegetab1e tallow (tallow treated with sulphuric acid and then neutralized), contained in water as a vehicle, is agitated while approximately 3 lbs. 10 ounces of wheat starch is gradually added and the mixture heated to 180 F. until the latter is thoroughly dispersed or dissolved. The approximate proportions of this mixture would then be-tallow 28 parts, starch 2 parts and water parts. Other solutions or emulsions such as Carnauba wax, paraffin wax, japan wax, etc., may be suitably employed.

As thus printed, the sheet I carries a\reticulated fine-lined pattern (or a discontinuous stippled pattern) as shown in Fig. 2 (Fig. 3) but preferably one in which the area actually covered by the resist may be smaller than the uncovered portion and which, at the same time, divides the latter up into individually small areas.

Upon leaving the roll 4 the sheet is passed between rollers 'I, 8, the lower of which receives a uniform layer of glue or other adhesive from tank 9 by means of applicator roll I 0. The sheet may then pass over rollers II, in festoons, to dry or through other drying apparatus of usual types. The dried sheet may then be taken up on rewinder (not shown) if desired. However, it may also be passed directly over a "breaker such as the knife edge I2 mounted (preferably at an angle to the sheet) between, and offset with respect to two guide rollers I3, I'4, and then taken up upon a rewinder I5, in finished condition. A second knife edge (set at substantially right angles to the rst) may also be used.

The coated sheet, before breaking, comprises the sheet ofl paper I, (see Fig. 4) carrying spaced deposits of resist I6, which may stand in low or high relief upon the surface of the sheet to form a reticulated pattern of lines or a dispersion of dots, and an intervening deposit of the adhesive or glue II which fills in between the pattern of lresist and may bridge over the same as at I8, to form a continuous layer. In the areas between the resist, the adhesive is firmly adherent to the paper sheet and may penetrate appreciably between the superficial fibres of the same. But such penetration does not form a continuous `stiff intermediate fibre reinforced layer, as heretofore. On the contrary, such areas are both small in extent and separated from each other by the intervening deposits of the resist which present relatively flexible areas of unstiifened paper, and gives the discontinuity necessary for non-curling. (With some resists, such areas may be rendered softer and more exible than the untreated paper).

Conversely, when a stippled pattern of resist is employed, a reticulated pattern of adhesive is formed therebetween.

Hence, in either case, the paper between the areas of adhesive is relatively free to ex. Moreover, since the resist and adhesive do not become rigidly attachedto each other, free flexing therebetween is feasible. Consequently, when the sheet passes over the breaker knife edge I2, the hardened glue deposits fracture without separating from the adjacent deposits of resist, and the continuous layer of adhesive above the resist, be-

ing of less cross-sectional dimension than the other portions, fractures more freely than a continuous deposit of uniform thickness. Accordingly, an innite number of fissures or fine cracks 20 vis produced throughout the adhesive so that there is no accumulation of stresses in the adhesive layer and the adhesive coated sheet does not tend to curl up but is relatively flexible and will lie flat.

As a modication of the invention above described, the resist may, as already indicated, comprise a discontinuous pattern, such as a stippling of fine dots, spaced apart from each other, thus leaving continuous spaces therebetween for the reception of the adhesive coating. In either case the adhesive may or may not cover the resist, according to the specific amounts required for the purposes which the gummed paper is to serve.

In the event that the adhesive is intended to cover the resist in appreciable areas, or to be applied to a continuous layer of resist as above mentioned, so that it must in large part or entirely adhere to the free surface of the resist, it is desirable to adapt the latter accordingly. It is found that this may be done by increasing the proportion of wheat starch relative to the tallow in the resist composition. For example, the following composition may be thus employed:

Parts Vegetable tallow 1A to 3 Wheat starch 12 Water 87.75 to the ingredients Ibeing mixed cold and heated to F. for a few minutes. Other adhesives may be used instead of wheat starch, such as gum arabic, dextrine, etc., and the amounts varied in accordance with the degree of viscosity, etc., required.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim: f

1. Method of preparing gummed paper, comprising applying toa sheet of paper a finely divided open pattern of resist and thereafter applying to the paper a continuous layer of adhesive and subjecting the coated sheetto breaking.

2. Method of preparing gummed paper, comprising as steps applying a resist to a sheet of paper in a finely divided open pattern, and coating the same with a uid adhesive, drying, and thereafter breaking the adhesive coating.

3. A sheet of gummed paper, comprising a finely divided open pattern of a resist, and a superposed substantially continuous coating of an adhesive, each in intimate association with the paper sheet.

4. A sheet of gummed paper, comprising a finely divided stippled pattern of a resist, andy a superposed coating of an adhesive, each in intimate association with the paper sheet.

5. A sheet of gummedpaper, comprising a finely divided reticulated pattern fof a resist, and a superposed complementary coating of an adhesive, each in intimate association with the paper sheet.

6. A sheet of gummed paper, comprising a finely divided dispersed pattern of a resist, and a superposed coating of an adhesive, each in intimate association with the paper sheet, said adhesive coating being traversed by a network of fine fissures.

7. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

8. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist comprising starch, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

9. The method of preparing gum paper which comprises applying to one side of a sheet of paper i a resist comprising tallow, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point'of brittleness, and tle coating, said resist serving torfacilitate the breaking operation.

10. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist comprising tallow, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

11. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist 4composed of starch, tallow and water,' thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then then breaking the britbreaking the brittle coating, said resist serving to facilitate the breaking operation.

12. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist approximately one-eighth starch and a few per cent tallow, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, `and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

' 13, The method of preparing gum paper which comprises applying to one side of a sheet .of paper a resist approximately one-fourth tallow and a few per cent starch, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

14. The method of preparing gum paper which comprises applying to one side of asheet of paper a resist lin a finely divided open pattern, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

15. The method of preparing gum paper which comprises applying to one side of a sheet of paper a resist in a finely divided reticulated pattern, thereafter applying on the same side a coating of liquid adhesive which is brittle when dry, drying the adhesive to the point of brittleness, and then breaking the brittle coating, said resist serving to facilitate the breaking operation.

. GARDNER R. ALDEN. 

